I have quite a few investments. It starts with my 401K (I make Roth Contributions) and I also have a separate Roth IRA. Like you would expect, I just send my money into them and never look at it. The nice part about having my Roth through a financial adviser is that they will rebalance and give me advice on where to allocate my 401K once a year.
I also have a Schwab account that I use to invest in stocks and ETFs. This is ideally going to be my "retirement" money when I retire early (fingers crossed) before I can start withdrawing from my 401K/Roth IRA. The nice part about this is that if I'm ever in a crunch for cash, I have the ability to sell some of my positions and withdraw from there. I would say I spend about 6 hours a month researching stocks to invest in and looking at the ones I already own. There will always be a lot of opinions out there on where a stock will head, but I just try to think "in the long-term, is this a company that's going to be around." I know, that's not the best advice, but I try not to get caught up in short-term volatility.
As far as picking stocks, a lot of the stocks I own are things I actually use. Apple, Whole Foods Market, TJ Maxx...Some aren't, but they're companies I've researched and like the products they offer (like oil, lol).